Valorization of Baker Yeast Industry Waste in Agriculture by Improving Germination and Growth of Barley and Pea.

Industrial waste still present an environmental danger for the nature and survival of all living beings. Among these toxic products, the focus has been on liquid effluents from the baker's yeast industry that cause real environmental problems mainly due to their pollutant load and the release of unpleasant odors. In order to minimize these hazards and to take advantage of these wastes for the sake of our environment, the present work consists on valorizing effluents from the baker's yeast industry on barley (Hordeum vulgare) and pea (Pisum sativum), two important agricultural products of Tunisian north-west. Results showed that this waste is characterized by its richness in organic matter, and the presence of proteins traces with high chemical and biochemical oxygen demand (COD and BOD₅) values. Diluted effluent at a dose of 2.5 mg/g significantly improves germination of both plant seeds by germination index (GI) calculation, to reach a maximum of 190 ± 17% and 150 ± 14% for barley and pea, respectively. In fertigation experiment, the use of a lower dose of .62 mg/g of diluted effluent promotes plant length to reach 52 ± 4 cm and 45 ± 1.4 cm, respectively, for H. vulgare and P. sativum. Gas chromatography coupled to mass spectrometry (GC-MS) analysis after derivatization showed significant enhancement of auxin production in pea treated with .62 mg/g of cream compared to control with a concentration of 10.60 ± .81 and 8.16 ± .43 ng/gFW, respectively. In another experiment, the irrigation of pea plants with furfural, as major compound of cream, promotes length and auxin production to reach 9.89 ± .56 ng/gFW for a furfural dose of .31 mg/g. This leads us to valorize baker's yeast effluent as an environment-friendly natural product in pea and barley agricultural and give insight to its mode of action.